PROBLEM TO BE SOLVED: To prevent decline of the cooling efficiency of an engine when the load of the engine is high in a combine harvester for reaping and harvesting.SOLUTION: The combine harvester has a controller (35) for driving a cooling fan (12) at a prescribed cooling reference rotational speed of forward rotation for sucking outside air into a dust preventive net (16) when a reaping and conveying part (8) and a threshing part (5) are driven or for accelerating and driving the cooling fan (12) to rotate forward the faster as the rotational speed of the engine (E) becomes the higher within a speed range lower than the cooling reference rotational speed when the reaping and conveying part (8) and the threshing part (5) are not driven.COPYRIGHT: (C)2012,JPO&INPIT【課題】刈取収穫作業を行うコンバインにおいて、エンジンの高負荷時におけるエンジンの冷却効率の低下を防止する。【解決手段】刈取搬送部(8)及び脱穀部(5)の駆動状態では、冷却ファン(12)を防塵ネット(16)の内側へ外気を吸気する正回転の所定の冷却基準回転速度で駆動し、刈取搬送部(8)及び脱穀部(5)の非駆動状態では、冷却ファン(12)を、前記冷却基準回転速度よりも低速の範囲内で、エンジン(E)の回転速度が高くなるほど増速して正回転駆動するコントローラ(35)を設ける。【選択図】図4